| Cover | Aug. 26, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 26, 2021 |
| Entity Registrant Name | LIMBACH HOLDINGS, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-36541 |
| Entity Tax Identification Number | 46-5399422 |
| Entity Address, Address Line One | 1251 Waterfront Place |
| Entity Address, Address Line Two | Suite 201 |
| Entity Address, City or Town | Pittsburgh |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 15222 |
| City Area Code | 412 |
| Local Phone Number | 359-2100 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, $0.0001 par value |
| Trading Symbol | LMB |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001606163 |
| Current Fiscal Year End Date | --12-31 |
